Answer:
A. Adult stem cells have unipotency, and embryonic stem cells have pluripotency.
Explanation:
The basic difference between a stem cell and a totipotent cell is that a stem cell has the potential to regenerate itself apart from producing other cells which are alike, for example hematopoietic stem cell. In contrast to this, a totipotent cell has the potential to develop into an entire organism but it cannot regenerate itself, for example zygote. Zygote can produce the entire organism but once zygote divides to form an embryo it can never become a zygote again.
In the early embryonic stages in mammals when the zygote divides to form 8 celled morula, each of the cell of morula retain its power of regeneration of an entire individual if allowed to develop separately but with advancement in development, the stem cells start to loose their potential to develop into the entire individual and they are confined to only pluripotency which means that they can only form an embryo and some parts of extra embryonic membranes not all of them.
Further when gastrula stage arrives, the power of cells to regenerate reduces even more and become restricted to only multipotency.
In the end, when the entire individual is developed the adult stem cells remain the only cells which have power of regeneration and they have unipotency which means that they can regenerate only one type of tissue. For example, skin cells are unipotent cells which can only regenerate skin.
